1. Field of the Invention
The present invention relates to a monolithic ceramic electronic component, and in particular, to a monolithic ceramic electronic component having a structure that includes a ceramic multilayer body including stacked ceramic layers; and outer electrodes arranged on surfaces of the ceramic multilayer body, the ceramic multilayer body including inner electrodes arranged therein, and the outer electrodes being electrically connected to the inner electrodes.
2. Description of the Related Art
As an example of a method for producing a monolithic ceramic capacitor, which is a typical monolithic ceramic electronic component, Japanese Unexamined Patent Application No. 2012-190874 discloses a method for producing a monolithic ceramic capacitor, as described below.
In the method for producing a monolithic ceramic capacitor described in Japanese Unexamined Patent Application Publication No. 2012-190874, first and second green sheets on which green inner electrode layers are formed are prepared, and then the first and second green sheets are alternately stacked in such a manner that electrostatic capacitance-forming portions lie on top of each other, thereby producing a green ceramic multilayer body.
The green ceramic multilayer body is cut into pieces corresponding to chip regions, thereby exposing extension portions of the green inner electrode layers at end surfaces of the pieces of the green ceramic multilayer body. A conductive paste is applied to the end surfaces of the pieces of the green ceramic multilayer body where the extension portions of the green inner electrode layers are exposed, thereby forming green underlying metal layers.
The pieces of the green ceramic multilayer body are fired to co-fire the green sheets, the green inner electrode layers, and the green underlying metal layers. Plating is performed on surfaces of underlying metal layers that have been produced by firing the green underlying metal layers.
Thereby, for example, a monolithic ceramic electronic component as illustrated in FIG. 2 is produced, the monolithic ceramic electronic component having a structure in which inner electrodes 102a and 102b are arranged in a ceramic multilayer body 110 so as to be located opposite each other with ceramic layers 101 and in which outer electrodes 104a and 104b are arranged on end surfaces 103a and 103b of the ceramic multilayer body 110 so as to be electrically connected to the inner electrodes 102a and 102b extending to the end surfaces 103a and 103b, respectively, which differ from each other, of the ceramic multilayer body 110.
In the production method described in Japanese Unexamined Patent Application Publication No. 2012-190874, the conductive paste is applied to the end surfaces of the pieces of the green ceramic multilayer body and baked. That is, the applied conductive paste is co-fired with the pieces of the green ceramic multilayer body. Thus, the outer electrodes disadvantageously have a large thickness (usually, about 10 μm or more), thereby increasing dimensions of a monolithic ceramic capacitor as a product.
In particular, in the case of a built-in monolithic ceramic electronic component for a multilayer substrate, the built-in monolithic ceramic electronic component being required to minimize the thickness dimension, i.e., height dimension, of a product, the thickness of the outer electrodes has a non-negligible effect on the thickness dimension, i.e., height dimension, of a product.
Here, it is conceivable that the thickness of the conductive paste applied is reduced by reducing the specific gravity of the conductive paste. In other words, it is conceivable that the conductive paste is applied so as to have a smaller thickness. In this case, the continuity of the electrodes is disadvantageously reduced at edge line portions (corner portions) of a ceramic multilayer body, thus leading to insufficient reliability.
Japanese Patent No. 5287658 discloses a method for producing a ceramic electronic component (in an embodiment, a monolithic ceramic capacitor) as described below.
In the method described in Japanese Patent No. 5287658, a predetermined number of ceramic green sheets for outer layers having no inner electrode pattern are stacked. A predetermined number of ceramic green sheets on which a first inner electrode pattern is formed by printing and a predetermined number of ceramic green sheets on which a second inner electrode pattern is formed by printing are alternately stacked thereon. A predetermined number of the ceramic green sheets for outer layers having no inner electrode pattern are stacked thereon. Thereby, a mother multilayer body is produced.
Outer terminal electrode patterns to be formed into first and second outer terminal electrodes are formed on upper and lower surfaces of the resulting mother multilayer body by screen printing or the like.
The mother multilayer body is divided by cutting at predetermined positions into individual ceramic multilayer bodies (green ceramic bodies). The ceramic multilayer bodies are subjected to barrel polishing. Then a conductive paste is applied to end surfaces and baked to form the outer terminal electrodes. Thereby, ceramic electronic components are produced.
In the method for producing a ceramic electronic component (in an embodiment, a monolithic ceramic capacitor) described in Japanese Patent No. 5287658, the outer terminal electrode patterns to be formed into portions of the first and second outer terminal electrodes extending from the end surfaces to the upper and lower surfaces (side surfaces) are formed by the screen printing or the like. It is thus possible to reduce the thickness of the outer terminal electrodes on the upper and lower surfaces (side surfaces) of the ceramic multilayer body, compared with the thickness described in Japanese Unexamined Patent Application Publication No. 2012-190874. This results in a reduction in the thickness dimension (height dimension) of the ceramic electronic component.
In the method described in Japanese Patent No. 5287658, however, although the thickness of the outer terminal electrodes on the upper and lower surfaces can be reduced, the thickness is reduced to the extent of about 5 μm. If the thickness is further reduced, the electrodes are ground at the time of barrel polishing treatment to make the edge lines round after the mother multilayer body is divided into pieces. This disadvantageously leads to the failure of subsequent plating and a reduction in conduction reliability.